As technology becomes ubiquitous in society, security becomes more and more important. This is especially true for content creators (e.g., musicians, actors, music studios, movie studios, etc.). Because the delivery medium for entertainment is so rapidly evolving, it becomes increasingly difficult for companies and individuals to monitor and manage copyrighted material. This has led to a large increase in the interest of Digital Rights Management (DRM). DRM can be used to restrict usage and/or unauthorized but effective duplication or redistribution of proprietary hardware, software and copyrighted works. The term DRM is also sometimes referred to as “copy protection,” “technical protection measures,” “copy prevention,” or “copy control.”
Some methods of DRM use digital certificates and/or public key infrastructure (PKI). PKI enables the secure electronic transfer of information between two or more devices without requiring both parties to have prior knowledge of a shared secret key (such as required in solely symmetric key encryption). Standards have been developed for various implementations, such as X.509, which is a standard for PKI and privilege management infrastructure (PMI). However, problems still exist, particularly when the private key corresponding to the subject public key within a certificate is suspected of having been compromised and therefore needs to be revoked. Thus, additional methods are needed to address the shortcomings of the current methods used for ensuring content security.